Speciation - Macroevolution
What is a Species?
What is a Species?
• Morphological species• Problems?
Variable Morphology
Grown in water Grown on land
Figure 14.3a
What is a Species?
• Biological Species Concept– Population– Interbreed– Fertile offspring– Reproductive isolation
Reproductive Isolation
Isolating Mechanisms
• Prezygotic isolation
• Postzygotic isolation
Figure 14.4
Prezygotic IsolationBehavioral Isolation
Prezygotic Isolation
Temporal Isolation
Prezygotic Isolation
Ecological Isolation
Prezygotic Isolation
Mechanical Isolation
Prezygotic Isolation
Gametic Mortality
Postzygotic Mechanisms
• Hybrid inviability
• Hybrid sterility
• Hybrid breakdown
Figure 14.3D
Mechanisms of Speciation
• Allopatric speciation
– Barrier prevents gene flow
• Sympatric speciation
– W/in home range
Figure 14.7
Allopatric Speciation
A. harrisi A. leucurus
Figure 14.4
– Isolation in Death Valley• New species of pupfish
Figure 14.5B A pupfish
Allopatric Speciation
Figure 14.9
Sympatric Speciation • Polyploidy
• Change in chromosome number (3n, 4n, etc.)
Parent species
Meioticerror
Self-fertilization
Offspring may be viable and self-fertile
Zygote
Unreduced diploid gametes
2n = 6Diploid
4n = 12Tetraploid
O. gigas
O. lamarckiana
AA BB
AB
AA BB DD
ABD
AA BB DD
Triticum monococcum(14 chromosomes)
Wild Triticum(14 chromosomes)Sterile hybrid
(14 chromosomes)
Meiotic error andself-fertilization
T.turgidumEmmer wheat(28 chromosomes)
T.tauschii(wild)(14 chromosomes)
Sterile hybrid(21 chromosomes)
Meiotic error andself-fertilization
T.aestivumBread wheat(42 chromosomes)
Possible Evolution of Wheat
Figure 14.7B
Models for Speciation
• Gradual change model– Small changes over time
• Punctuation model– Brief period near divergence
Figure 14.12
How have complex structures evolved?
•Many stages• From simpler versions w/ the same basic
function
Figure 14.11
Light-sensitivecells
Light-sensitivecells
Fluid-filled cavity Transparent protectivetissue (cornea)
Cornea
Layer of light-sensitivecells (retina)
Nervefibers
Nervefibers
Opticnerve
Opticnerve
Opticnerve
Eyecup Retina
Lens
Patch of light-sensitive cells Eyecup
Simple pinholecamera-type eye
Eye withprimitive lens
Complexcamera-type eye
Limpet Abalone Nautilus Marine snail Squid
• Changes in development
• Timing and rate of growth
How?
Figure 14.12A
Figure 14.12B
Chimpanzee fetus Chimpanzee adult
Human fetus Human adult
Stephen Jay Gould (evolutionary biologist)
Mickey Mouse “evolved”
Copyright DisneyEnterprises, Inc.
Mickey?
• Evolutionary trends do not mean that evolution is goal directed
Figure 14.13
Hippidion and other genera
Nannippus
NeohipparionHipparion
Sinohippus Megahippus
Archaeohippus
Callippus
HypohippusAnchitherium
Miohippus
Parahippus
Paleotherium
Propalaeotherium
Pachynolophus Orohippus
Epihippus
Equus
Pliohippus
Merychippus
Mesohippus
HyracotheriumGrazersBrowsers
EO
CE
NE
OL
IGO
CE
NE
MIO
CE
NE
PL
IOC
EN
EE
R
EC
EN
TP
LE
IST
OC
EN
End Goal? No!
• Rocks and fossils – Radiometric dating
• radioactive isotopes
Geologic Record
Figure 14.17
Figure 14.16
Table 15.1
• Impact on macroevolution?
Edge of one plate being pushed over edge ofneighboring plate (zones of violent geologic events)
Antarctic Plate
AustralianPlate
Splitdeveloping
IndianPlate
Eurasian PlateNorth
AmericanPlate
SouthAmerican
Plate
NazcaPlate
PacificPlate
ArabianPlate
AfricanPlate
Figure 15.3A
Continental drift
Figure 15.3B
0
65
135
245
Mill
ions
of
years
ago
Pale
ozo
icM
esozo
icC
en
ozo
ic
North AmericaEurasia
Africa
South America
India
AntarcticaAustralia
Laurasia
Gondwana
Pang
aea
Continental drift
• Volcanoes and earthquakes
San Andreas Fault
NorthAmericanPlate
San FranciscoSanta Cruz
Los Angeles
PacificPlate
California
Figure 15.4A, B
Figure 14.18
• Permian and Cretaceous periods– Dinosaurs?
Mass extinctions
Adaptive Radiation
• Burst of divergence • Single lineage gives rise to
many new species• New species fill vacant
adaptive zone
Hawaiian Islands
Adaptive radiations:– Honeycreepers
– Fruit flies (Drosophila) - 40% of fruit fly species are found in Hawaii
Hawaiian Honeycreepers
FOUNDER SPECIESFigure 18.7Page 297
Classifying Diversity
• Taxonomy• Phylogeny
– Homologous structures and molecular sequences
– Evidence of common ancestry
Figure 15.6
Ancestry? OrConvergent evolution?
PHYLOGENY
• Systematics– Connects
classification w/ evolution
• Binomial – Genus – Species
Phylogeny Species
Genus
Family
Order
Class
Phylum
Kingdom
Domain
Feliscatus
Felis
Felidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
Species
Feliscatus
(domesticcat)
Mephitismephitis
(striped skunk)
Lutralutra
(Europeanotter)
Canisfamiliaris
(domestic dog)
Canislupus(wolf)
Genus
Family
Order
Felis
Felidae
Carnivora
Mustelidae
Mephitis Lutra Canis
Canidae
Figure 15.7B
• Phylogenetic treePHYLOGENY
Figure 14.24
– The simplest (most parsimonious) hypothesis
Figure 15.8B
Lizards Snakes Crocodiles Birds
Common reptilian ancestor
CLADOGRAMS